The invention is particularly applicable to remote toll systems that enable transactions to be performed between control stations and vehicles travelling at high speeds. The invention is also applicable to access control for persons provided with equipment that is capable of communicating over short distances with access control stations.
In general, such communication takes place via electromagnetic waves or via light waves. Such waves offer short communication times as a result firstly of authorized communication time, and secondly of the ratio of the size of the zone in which communication is possible (the zone covered by the waves) divided by the speed of the mobile. However, existing smart cards are designed for applications in which there are no major constraints concerning the speed at which the card must be read, e.g. in banking or telephone applications.
Therefore, the constraint concerning the shortness of the duration of the communication and of the transaction, for remote transactions, is generally incompatible with the performance levels of currently known smart cards.
To solve that problem, one known solution consists in storing data from the card in a fast memory of the on-board reader on inserting the card into the on-board reader, so that during the transaction, it is the data stored in the fast memory of the on-board reader that is transferred via electromagnetic waves or via light waves to the fixed station, thereby enabling the data to be transferred quickly and thus making the transaction possible.
The fast memory of the on-board reader is loaded automatically by means of a presence-detecting contact which triggers an automatic updating procedure to update the fast memory of the on-board reader.
Although that solution enables data to be transferred quickly during the transaction, it nevertheless suffers from a major drawback: there is no guarantee that the data stored in the fast memory of the reader is genuinely the same as the data contained in the card that is actually inserted into the reader at the time of the transaction, because tampering is possible.
After having inserted a first card which triggers updating of the memory of the on-board reader, a dishonest person might lock the card-detecting contact mechanically, and insert a new card. In this way, at the time of the transaction, the fixed equipment will receive data relating to a card that is not inserted in the reader. Other types of fraud are also possible.